GIS-Based Spatial Mapping of Flash Flood Hazard in Makkah City, Saudi Arabia

Abstract

Flash floods occur periodically in Makkah city, Saudi Arabia, due to several factors including its rugged to-pography and geological structures. Hence, precise assessment of floods becomes a more vital demand in development planning. A GIS-based methodology has been developed for quantifying and spatially mapping the flood characteristics. The core of this new approach is integrating several topographic, metrological, geological, and land use datasets in a GIS environment that utilizes the Curve Number (CN) method of flood modelling for ungauged arid catchments. Additionally, the computations of flood quantities, such as depth and volume of runoff, are performed in the attribute tables of GIS layers, in order to assemble all results in the same environment. The accomplished results show that the runoff depth in Makkah, using a 50-years re-turn period, range from 128.1 mm to 193.9 mm while the peak discharge vary from 1063 m<sup>3</sup>/s to 4489 m<sup>3</sup>/s. The total flood volume is expected to reach 172.97 million m<sup>3</sup> over Makkah metropolitan area. The advan-tages of the developed methodology include precision, cost-effective, digital outputs, and its ability to be re-run in other conditions

Application of remote sensing and GIS-based hydrological modelling for flood risk analysis: a case study of District 8, Ho Chi Minh city, Vietnam

“…For the SCS method of predicting flooding, CN values are obtained from LULC features and vary with the type of LULC, so LULC plays a vital role in affecting and determining the runoff volume for sub-catchments. The results support the findings of Dawod et al (2011) who also concluded that the higher the CN values of sub-catchments were, the higher the runoff and flood hazards.…”

“…This may explain why some sub-catchments which had a lot of impervious areas were not flooded, for example sub-catchment 1. Dawod et al (2011) concluded that flow length is one of the main factors affecting runoff and flood risk in urban areas. Long et al (2010) argued that once flow length of sub-catchments increases, the values of bankfull discharge will be improved, and so the flood hazard will logically be reduced in areas with a high rate of flow length.…”

“…This model uses runoff depth data obtained from SCS-CN as an input to determine the peak discharge of watersheds and enables the model to effectively simulate runoff and peak discharge to identify flood phenomenon in urban areas (Seeni Mohd and Mansor 2000;HolmanÀDodds et al 2003;Ramana 2014). The SCS-CN method, as included in TR-55, is widely used for predicting direct runoff volume for a given rainfall event, especially in urban areas (Kim et al 2010;Dawod et al 2011;Soulis and Valiantzas 2011;Gajbhiye and Mishra 2012). A number of studies have found that the SCS-CN method is the most effective method for determining runoff volume and peak discharge, examples include Kim et al (2010); Soulis and Valiantzas (2011); Dawod et al (2011); Gajbhiye and Mishra (2012) and Shadeed and Almasri (2010).…”

Flash flood hazard mapping: A pilot case study in Xiapu River Basin, China

“…Dawod et al (2011) utilized the curve number (CN) method to model flash floods for ungauged arid catchments and then integrated the results with topographic, metrological, geological, and land use datasets in order to quantify and spatially map the flood characteristics; Bajabaa et al (2014) produced a flash flood hazard map by combining GIS techniques and physiographic features of the study area; Fernandez-Lavado et al (2007) derived flood hazard maps from a comprehensive geomorphological map, and classified flood hazards into three levels (very high, high, and moderate). In China, the main purpose of flash flood hazard mapping is currently to aid in community emergency planning, and flash flood hazard mapping is still at an early stage (Li et al, 2013).…”

Hydrological Modeling Using GIS for Mapping Flood Zones and Degree Flood Risk in Zeuss-Koutine Basin (South of Tunisia)

“…The consequences of the floods vary from a medium with another and are primarily related to the distance which separates the urban areas, the agricultural lands and the installations of the floodplains [10], it is thus the preliminary study for the prevention against these risks of floods proves to be paramount for the protection or the reduction of the possible damage.…”